Glass Glazing Bead Weatherstip

I guess that is what you would call it ?
So the old weatherstrip is pulled out in the corners of a couple windows along with a nice gap where it is suppose to butt-up.

I got the rear window strip to seat back in, but the front one above cab , the rubber is just too stiff/old ?
So I ordered new rubber seal to go around both windows.
I pulled off the front old weatherstrip (glazing bead) cleaned the channel out , taped the painted frame and then took 0000 steel wool and cleaned up the window , got all the water spots etc off.
Ok now for the question part, when putting the new rubber strip on, in the corners it will not lay flat on the glass, bows out !

Does anybody have any tricks or ? to get the rubber to lay flat ?

I let the new rubber seal lay out in the sun to get a little warm then put it in around the window, two corners seated pretty good, but two just will not sit flat on the glass no matter what I do ???

Thanks for any input !